This type of design features safety spring-driven sealed units with no electromagnetic actions. They are extremely safe and can be use even when power is not available, and they can also remain stopped for long periods of time to prevent damage to machines.Most of these products feature superior performance, and Chain Tail has more than years of manufacturing experience in this category.Through these years we have made considerable changes and improvements, and we lead the industry in quality and technology. We offer a wide range of models, all of which have won great praise from those who have used them.